Can my friend be charged with assault for this?

So, yesterday my friends and I were playing soccer to past the time. So, everything was smooth until the goalie kicked it and my friend deflected it sideways, to the biking path. The ball then rolled all the way into a biker's pedal and he literally flipped over. He wasn't hurt, but had a few minor cuts on his arms and legs. We tried to help him up, but he was hostile and told us to "get the **** away" and then called the police on his cell-phone. My friend was arrested and he won't be released until tuesday. What are the chances that he will be charged with assault? The guy is an honor roll student and was heading off to a good college this summer, and now his future and life may be ruined because of this!! Please help!!